It is hard to tell why reference mainboard turned out the most economical. All three mainboards have very similar formal specifications. For example, all of them have an additional IEEE1394 controller. The only difference is passive North Bridge cooler with heatpipe technology on MSI board. Maybe it is the absence of a fan that determined the slight difference in ASUS and MSI results.
Anyway, we don’t see ASUS P5N-D being economical. ASUS stresses that EPU technology is a hardware solution, which means it doesn’t require any drivers or special utilities. However, you will still need them in order to adjust the power-saving modes manually. So, let’s install ASUS EPU driver and AI Suite tool with the AI Gear 3 utility that we need.
Pretty gloomy AI Suite allows controlling frequencies, voltages, temperatures and rotation speeds of the monitored fans.
AI Suite includes Q-Fan 2 utility that allows controlling the rotation speed of connected fans. AI Booster utility overclocks the system, and AI Nap – switches the system into sleep mode. However, we are only going to talk about AI Gear3 utility at this time.
Once we completed the installation there appeared a tray icon corresponding to the selected power-saving mode that reported the current level of power consumption. That’s all this icon does. It cannot even launch AI Gear3. The only thing you can do with it is disable the pop-up windows.
AI Gear3 utility interface looks as follows:
At first you have to calibrate by clicking the system case and magnifying glass icon in the upper right corner. The utility will test through all modes real quick. The wrench icon opens Settings page where you can set the time when the system should switch to AI Nap mode.
The airplane icon indicates the default High Performance mode. It is the regular operational mode for your system CPU: in idle mode the clock multiplier will drop to x6 and under workload it will go back to its default value. It is really strange that a common mode like that got such a loud name. There is one drawback though: Intel power-saving technologies do not work as they should in this case. Namely, the clock frequency multiplier will be lowered, while the voltage will remain unchanged.
A car icon stands for Medium Power Saving. In this case the mainboard acts tricky: it lowers the FSB frequency and voltage below the nominal. We tested out this mode with an Intel Core 2 Duo E4300 processor: its default 200MHz FSB was lowered to 190MHz. for Intel Core 2 Duo E8400 the 333MHz FSB dropped to 316MHz. everything else remained the same: the frequency multiplier dropped to x6 in idle mode and then returned back to the nominal setting of x9.
Only in Max. Power Saving mode marked with a pedestrian the system consumed very little power. In this case the FSB frequency remained low, the voltage was set a little below the nominal value and the CPU is forced to stay in its most economical mode: the multiplier is set at x6 and doesn’t increase even under workload. However, you save the power at the expense of performance. We didn’t buy a CPU to have it running half-way.
But the funniest thing was Max. Performance mode marked with a rocket. In this case the FSB frequency increases to 210MHz for CPUs with 200MHz FSB and to 350MHz for those with 333MHz FSB and they call it “Turbo-mode”. The only reasonable mode is marked with a star and is called Auto. As you may have already figured out, the system will set the most appropriate power-saving mode depending on the CPU workload.
So, ASUS EPU technology replaced standard power-saving technologies from Intel and expanded their functionality by dropping the voltage below the nominal. It works in exactly the same way as the utility for Gigabyte DES. However, it could be a nice software replacement for standard power-saving technologies from Intel, since they get disabled on ASUS mainboards during overclocking anyway. Even though AI Suite, EPU driver and Nap driver will be always on. Unfortunately, AI Gear3 utility shuts down during overclocking, just like Gigabyte DES. So, it is absolutely useless for overclockers.
Attention: In fact, you’d better not install AI Suite at all or use some uninstaller tool. You can delete EPU and Nap drivers, but the aaCenter.exe file from AI Suite will stay in the memory forever and will remind of itself by the following error messages: